Abnormal Myocardial Blood Flow Reserve Observed in Cardiac Amyloidosis

Abstract

We performed real-time myocardial contrast echocardiography on a patient with cardiac amyloidosis and previous normal coronary angiography presenting with atypical chest pain to assess myocardial blood flow reserve (MBFR). Myocardial contrast echocardiography was performed and flash microbubble destruction and replenishment analysis was used to calculate myocardial blood flow. Dipyridamole was used to achieve hyperemia. MBFR was derived from the ratio of peak myocardial blood flow at hyperemia and rest. The results show a marked reduction in MBFR in our patient. Previous reports of luminal obstruction of intramyocardial rather than epicardial vessels by amyloid deposition may be causing microvascular dysfunction.

Coronary microvascular disease in hypertrophic and infiltrative cardiomyopathies

“… 77 – 80 Although most studies have focused on the non-bioptic identification of cardiac amyloid depositions, a few smaller studies have also assessed the microvasculature in CA using all available imaging modalities. 76 , 81 – 85 In patients with both AL-CA and ATTR-CA and in the absence of epicardial CAD that were assessed with 13 N-ammonia PET, rest MBF, hyperemic MBF and MFR were significantly lower when compared to a matched hypertensive patients’ group with LVH. 76 (Figure 3 ).…”

“… 82 , 87 Real-time contrast TTE with flash bubble destruction has also been used for quantification of MBF in AL CA patients, whereby significant reduction of hyperemic MBF was observed. 85 Even in patients with rare renal amyloid A (AA) amyloidosis, MFR was significantly lower at contrast-TTE compared to a group of individuals with non-amyloid chronic inflammatory disease and healthy controls. 81 As cardiac involvement in AA amyloidosis usually occurs at later stages of the disease, assessment of microvascular function could potentially enable earlier identification of patients at risk.…”

A study protocol for an observational cohort investigating cardiac transthyretin amyloidosis flow reserve before and after Tafamidis treatment: The AMYTRE study

“…They found lower stress and rest myocardial blood flow (MBF) and lower myocardial flow reserve (MFR) in their cardiac PET study (using 13 N), including 21 patients with definite cardiac amyloidosis without epicardial CAD ( 4 ). Moreover, reduction of MFR during cardiac amyloidosis has also been described using myocardial contrast echocardiography ( 5 ).…”